Humans have long dreamed about reaching out and exploring space. Most science fiction, more often than not, portrays cities on the dusty lunar surface and Mars.
And if you listen to some billionaires like Elon Musk and Jeff Bezos, cities on the moon are coming soon.
In fact, in February, SpaceX CEO Musk posted on social media that the company was shifting its focus away from settling on Mars — something Musk has been passionate about for the past decade.
“For those unaware, SpaceX has already shifted focus to building a self-growing city on the moon, as we can potentially achieve that in less than 10 years, whereas Mars would take 20+ years,” he wrote.
This statement — and those of Blue Origin CEO Bezos, who has claimed “millions of people” will be living in space by 2045 — intrigued Martin Elvis, senior astrophysicist at Harvard University’s Smithsonian Astrophysical Observatory.
He, along with astrophysicist Jonathan McDowell, honorary professor at the Durham University Space Research Centre in England, decided to take a look at the numbers.
But their findings, it turns out, aren’t great for a lunar civilization, so don’t start packing just yet.
In their paper, published in the journal Frontiers in Space Technologies, the pair decided to examine power and water needed to sustain humans on the moon.
When it comes to power, they found that solar and nuclear would be enough to sustain one million people on the lunar surface.
But then there’s water.
It may be surprising to some, but there is water on the moon. It’s believed that most of it is contained in permanently shadowed regions (PSR), areas at the poles that never see sunlight.
But in this study, they found that there’s not enough on the moon to sustain a large human presence on the lunar surface.
“Our work shows that, yeah, if you want to have an Antarctic base on the moon for the next few hundred years, no problem. If you want to have a small town, that’s doable. If you want to cover the face of the moon with cities, like in the best science fiction, then you have to find a way to get the water there, because it’s not there right now,” McDowell said.
Assuming that there is roughly one billion tonnes of water on the moon, which is in line with current estimates, they found that a civilization of one million people would only be able to live on the moon for roughly 100 years. And that’s only if we can recycle 98 per cent of the water, which is what is done on the International Space Station.
‘A small lake’
Elvis said that while one billion tonnes of water sounds like a lot, you have to put it in perspective.
“If you had a huge aquarium the size of Central Park in Manhattan, you could fill it up to where the Statue of Liberty was just underwater and that’s the amount of water you’ve got. So it’s huge in one way, but … it’s a small lake. And a small lake is not going to supply a big city for very long.”
That’s not to say that humans can’t ever live on the moon. If it were a town of 10,000, they found that would be sustainable for centuries.
However, that’s assuming that the one billion tonnes of water is an accurate estimate.
“Very likely a billion is way overestimating. It’s probably 20 or 30 times too big,” Elvis said.
Jacob Bleacher, NASA’s chief exploration scientist, says the first two Artemis missions have set the stage for the next moon landing, a moon base and eventually, human exploration of Mars, missions so challenging that only international co-operation makes them possible.
He also said that it’s unlikely that we’d be able to recover all the water that’s available. Instead, it would be more like one-third to half of what is present.
“So my best guess is the real amount of water available that we can be fairly confident about is one per cent of what we said before. So instead of 100 years, it’s one year.”
And there’s one other thing: We don’t know in what form that water exists. And we need to figure that out.
“It’s one thing to detect it from satellites, but … there are uncertainties in those measurements,” said Gordon Osinski, a professor in planetary geology at Western University in London, Ont.
“I think it is there, but let’s go and ground-truth that and confirm it. And then there’s the bigger unknowns of what form it’s in…. Is it more like the permafrost up in the Arctic, where it’s basically soil with, you know, sub-millimetre size ice crystals, which are hard to get out of?”
While this may sound like pessimistic news for humanity’s plans to explore the cosmos, McDowell said it’s best to know what you’re dealing with.
“The truth is never negative,” he said. “What’s negative is to actually go and try and do something that isn’t going to work.”
